“How does it feel to be number one, Edinburgh?” Noel Fielding asks the packed Festival Theatre audience. A wall of deafening screams is his reply, which can probably be interpreted as a positive response. It's fitting that the Mighty Boosh have chosen to open their biggest tour to date in Edinburgh. It was at the Fringe festival that Fielding and his co-star Julian Barratt first gained recognition for their unique brand of sweet, surreal humour, winning the Best Newcomer award in 1998. Back then, the Boosh were playing in a sweaty subterranean room in the Cowgate. Tonight they are playing the city's largest theatre, the first of two sold-out performances. This is more than an opening night; it marks a triumph for the Boosh brand.

But Fielding doesn't look much like a returning conqueror: dressed in his trademark sparkly silver jump suit and gold ballet shoes, he has a grin wider than the Cheshire cat in Alice in Wonderland and is clearly relishing being back on stage. He paces around frantically in the opening minutes, trying to burn off his excess energy. It takes Barratt to bring him back down to earth. “So, what have you been up to since the series?” he asks his partner casually. “Oh you know, keeping a low profile” replies a suddenly sheepish Fielding. Barratt doesn't miss a beat: “Yeah, I heard about your low profile. In the newspapers, mostly.”

Its the combination of Fielding's infectious enthusiasm and Barratt's dry, laconic wit that has made the Boosh the success it is. What makes it special is the huge variety of characters involved, and the array of fantastical worlds they inhabit. Tonight, the old favourites are out in force. Bob Fossil runs around creating havoc, while Tony Harrison fronts his own chatshow.

This being a Mighty Boosh live show, there is a delightfully shambolic feel to proceedings. There's no attempt made to stick to any sort of script, and what little structure the show has is often forgotten. It being the opening night, there are also unintentional gaffes galore. But every time they fluff a line, the crowd laughs all the more. Nobody attends a Boosh show expecting a carefully choreographed piece of theatre. They want the unexpected, the surreal, and the downright daft. On those fronts, the show doesn't disappoint. It's left to Fielding to sum up what this all means. “The message is: if your life is shit, learn to accessorise!” Amen to that.